<!DOCTYPE HTML>
<html lang="zh-CN">


<head>
    <meta charset="utf-8">
    <meta name="keywords" content="FFmpeg笔记(三), jiodg45的博客">
    <meta name="description" content="">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
    <meta name="renderer" content="webkit|ie-stand|ie-comp">
    <meta name="mobile-web-app-capable" content="yes">
    <meta name="format-detection" content="telephone=no">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
    <!-- Global site tag (gtag.js) - Google Analytics -->


    <title>FFmpeg笔记(三) | jiodg45的博客</title>
    <link rel="icon" type="image/png" href="/jiodg45/favicon.png">

    <link rel="stylesheet" type="text/css" href="/jiodg45/libs/awesome/css/all.css">
    <link rel="stylesheet" type="text/css" href="/jiodg45/libs/materialize/materialize.min.css">
    <link rel="stylesheet" type="text/css" href="/jiodg45/libs/aos/aos.css">
    <link rel="stylesheet" type="text/css" href="/jiodg45/libs/animate/animate.min.css">
    <link rel="stylesheet" type="text/css" href="/jiodg45/libs/lightGallery/css/lightgallery.min.css">
    <link rel="stylesheet" type="text/css" href="/jiodg45/css/matery.css">
    <link rel="stylesheet" type="text/css" href="/jiodg45/css/my.css">

    <script src="/jiodg45/libs/jquery/jquery.min.js"></script>

<meta name="generator" content="Hexo 5.4.0">
<style>.github-emoji { position: relative; display: inline-block; width: 1.2em; min-height: 1.2em; overflow: hidden; vertical-align: top; color: transparent; }  .github-emoji > span { position: relative; z-index: 10; }  .github-emoji img, .github-emoji .fancybox { margin: 0 !important; padding: 0 !important; border: none !important; outline: none !important; text-decoration: none !important; user-select: none !important; cursor: auto !important; }  .github-emoji img { height: 1.2em !important; width: 1.2em !important; position: absolute !important; left: 50% !important; top: 50% !important; transform: translate(-50%, -50%) !important; user-select: none !important; cursor: auto !important; } .github-emoji-fallback { color: inherit; } .github-emoji-fallback img { opacity: 0 !important; }</style>
</head>




<body>
    <header class="navbar-fixed">
    <nav id="headNav" class="bg-color nav-transparent">
        <div id="navContainer" class="nav-wrapper container">
            <div class="brand-logo">
                <a href="/jiodg45/" class="waves-effect waves-light">
                    
                    <img src="/jiodg45/medias/logo.png" class="logo-img" alt="LOGO">
                    
                    <span class="logo-span">jiodg45的博客</span>
                </a>
            </div>
            

<a href="#" data-target="mobile-nav" class="sidenav-trigger button-collapse"><i class="fas fa-bars"></i></a>
<ul class="right nav-menu">
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/jiodg45/" class="waves-effect waves-light">
      
      <i class="fas fa-home" style="zoom: 0.6;"></i>
      
      <span>首页</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/jiodg45/tags" class="waves-effect waves-light">
      
      <i class="fas fa-tags" style="zoom: 0.6;"></i>
      
      <span>标签</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/jiodg45/categories" class="waves-effect waves-light">
      
      <i class="fas fa-bookmark" style="zoom: 0.6;"></i>
      
      <span>分类</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/jiodg45/archives" class="waves-effect waves-light">
      
      <i class="fas fa-archive" style="zoom: 0.6;"></i>
      
      <span>归档</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/jiodg45/about" class="waves-effect waves-light">
      
      <i class="fas fa-user-circle" style="zoom: 0.6;"></i>
      
      <span>关于</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/jiodg45/contact" class="waves-effect waves-light">
      
      <i class="fas fa-comments" style="zoom: 0.6;"></i>
      
      <span>留言板</span>
    </a>
    
  </li>
  
  <li class="hide-on-med-and-down nav-item">
    
    <a href="/jiodg45/friends" class="waves-effect waves-light">
      
      <i class="fas fa-address-book" style="zoom: 0.6;"></i>
      
      <span>友情链接</span>
    </a>
    
  </li>
  
  <li>
    <a href="#searchModal" class="modal-trigger waves-effect waves-light">
      <i id="searchIcon" class="fas fa-search" title="搜索" style="zoom: 0.85;"></i>
    </a>
  </li>
</ul>


<div id="mobile-nav" class="side-nav sidenav">

    <div class="mobile-head bg-color">
        
        <img src="/jiodg45/medias/logo.png" class="logo-img circle responsive-img">
        
        <div class="logo-name">jiodg45的博客</div>
        <div class="logo-desc">
            
            Never really desperate, only the lost of the soul.
            
        </div>
    </div>

    

    <ul class="menu-list mobile-menu-list">
        
        <li class="m-nav-item">
	  
		<a href="/jiodg45/" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-home"></i>
			
			首页
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/jiodg45/tags" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-tags"></i>
			
			标签
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/jiodg45/categories" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-bookmark"></i>
			
			分类
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/jiodg45/archives" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-archive"></i>
			
			归档
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/jiodg45/about" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-user-circle"></i>
			
			关于
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/jiodg45/contact" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-comments"></i>
			
			留言板
		</a>
          
        </li>
        
        <li class="m-nav-item">
	  
		<a href="/jiodg45/friends" class="waves-effect waves-light">
			
			    <i class="fa-fw fas fa-address-book"></i>
			
			友情链接
		</a>
          
        </li>
        
        
        <li><div class="divider"></div></li>
        <li>
            <a href="https://github.com/blinkfox/hexo-theme-matery" class="waves-effect waves-light" target="_blank">
                <i class="fab fa-github-square fa-fw"></i>Fork Me
            </a>
        </li>
        
    </ul>
</div>


        </div>

        
            <style>
    .nav-transparent .github-corner {
        display: none !important;
    }

    .github-corner {
        position: absolute;
        z-index: 10;
        top: 0;
        right: 0;
        border: 0;
        transform: scale(1.1);
    }

    .github-corner svg {
        color: #0f9d58;
        fill: #fff;
        height: 64px;
        width: 64px;
    }

    .github-corner:hover .octo-arm {
        animation: a 0.56s ease-in-out;
    }

    .github-corner .octo-arm {
        animation: none;
    }

    @keyframes a {
        0%,
        to {
            transform: rotate(0);
        }
        20%,
        60% {
            transform: rotate(-25deg);
        }
        40%,
        80% {
            transform: rotate(10deg);
        }
    }
</style>

<a href="https://github.com/blinkfox/hexo-theme-matery" class="github-corner tooltipped hide-on-med-and-down" target="_blank"
   data-tooltip="Fork Me" data-position="left" data-delay="50">
    <svg viewBox="0 0 250 250" aria-hidden="true">
        <path d="M0,0 L115,115 L130,115 L142,142 L250,250 L250,0 Z"></path>
        <path d="M128.3,109.0 C113.8,99.7 119.0,89.6 119.0,89.6 C122.0,82.7 120.5,78.6 120.5,78.6 C119.2,72.0 123.4,76.3 123.4,76.3 C127.3,80.9 125.5,87.3 125.5,87.3 C122.9,97.6 130.6,101.9 134.4,103.2"
              fill="currentColor" style="transform-origin: 130px 106px;" class="octo-arm"></path>
        <path d="M115.0,115.0 C114.9,115.1 118.7,116.5 119.8,115.4 L133.7,101.6 C136.9,99.2 139.9,98.4 142.2,98.6 C133.8,88.0 127.5,74.4 143.8,58.0 C148.5,53.4 154.0,51.2 159.7,51.0 C160.3,49.4 163.2,43.6 171.4,40.1 C171.4,40.1 176.1,42.5 178.8,56.2 C183.1,58.6 187.2,61.8 190.9,65.4 C194.5,69.0 197.7,73.2 200.1,77.6 C213.8,80.2 216.3,84.9 216.3,84.9 C212.7,93.1 206.9,96.0 205.4,96.6 C205.1,102.4 203.0,107.8 198.3,112.5 C181.9,128.9 168.3,122.5 157.7,114.1 C157.9,116.9 156.7,120.9 152.7,124.9 L141.0,136.5 C139.8,137.7 141.6,141.9 141.8,141.8 Z"
              fill="currentColor" class="octo-body"></path>
    </svg>
</a>
        
    </nav>

</header>

    



<div class="bg-cover pd-header post-cover" style="background-image: url('/jiodg45/medias/featureimages/17.jpg')">
    <div class="container" style="right: 0px;left: 0px;">
        <div class="row">
            <div class="col s12 m12 l12">
                <div class="brand">
                    <h1 class="description center-align post-title">FFmpeg笔记(三)</h1>
                </div>
            </div>
        </div>
    </div>
</div>




<main class="post-container content">

    
    <link rel="stylesheet" href="/jiodg45/libs/tocbot/tocbot.css">
<style>
    #articleContent h1::before,
    #articleContent h2::before,
    #articleContent h3::before,
    #articleContent h4::before,
    #articleContent h5::before,
    #articleContent h6::before {
        display: block;
        content: " ";
        height: 100px;
        margin-top: -100px;
        visibility: hidden;
    }

    #articleContent :focus {
        outline: none;
    }

    .toc-fixed {
        position: fixed;
        top: 64px;
    }

    .toc-widget {
        width: 345px;
        padding-left: 20px;
    }

    .toc-widget .toc-title {
        padding: 35px 0 15px 17px;
        font-size: 1.5rem;
        font-weight: bold;
        line-height: 1.5rem;
    }

    .toc-widget ol {
        padding: 0;
        list-style: none;
    }

    #toc-content {
        padding-bottom: 30px;
        overflow: auto;
    }

    #toc-content ol {
        padding-left: 10px;
    }

    #toc-content ol li {
        padding-left: 10px;
    }

    #toc-content .toc-link:hover {
        color: #42b983;
        font-weight: 700;
        text-decoration: underline;
    }

    #toc-content .toc-link::before {
        background-color: transparent;
        max-height: 25px;

        position: absolute;
        right: 23.5vw;
        display: block;
    }

    #toc-content .is-active-link {
        color: #42b983;
    }

    #floating-toc-btn {
        position: fixed;
        right: 15px;
        bottom: 76px;
        padding-top: 15px;
        margin-bottom: 0;
        z-index: 998;
    }

    #floating-toc-btn .btn-floating {
        width: 48px;
        height: 48px;
    }

    #floating-toc-btn .btn-floating i {
        line-height: 48px;
        font-size: 1.4rem;
    }
</style>
<div class="row">
    <div id="main-content" class="col s12 m12 l9">
        <!-- 文章内容详情 -->
<div id="artDetail">
    <div class="card">
        <div class="card-content article-info">
            <div class="row tag-cate">
                <div class="col s7">
                    
                    <div class="article-tag">
                        
                            <a href="/jiodg45/tags/audio/">
                                <span class="chip bg-color">audio</span>
                            </a>
                        
                            <a href="/jiodg45/tags/ffmpeg/">
                                <span class="chip bg-color">ffmpeg</span>
                            </a>
                        
                    </div>
                    
                </div>
                <div class="col s5 right-align">
                    
                    <div class="post-cate">
                        <i class="fas fa-bookmark fa-fw icon-category"></i>
                        
                            <a href="/jiodg45/categories/ffmpeg/" class="post-category">
                                ffmpeg
                            </a>
                        
                    </div>
                    
                </div>
            </div>

            <div class="post-info">
                
                <div class="post-date info-break-policy">
                    <i class="far fa-calendar-minus fa-fw"></i>发布日期:&nbsp;&nbsp;
                    2021-03-11
                </div>
                

                

                

                

                
            </div>
        </div>
        <hr class="clearfix">

        

        

        <div class="card-content article-card-content">
            <div id="articleContent">
                <h2 id="视频编码格式-H-261笔记"><a href="#视频编码格式-H-261笔记" class="headerlink" title="视频编码格式-H.261笔记"></a>视频编码格式-H.261笔记</h2><p>H.261是1990年ITU-T定制的一个视频编码标准,属于视频编解码器,视频编码器的鼻祖<br>H.261又称为P*64，其目是为了能在64kbps的带宽上传输质量可接受的视频信号，<br>编码程序设计的码率是能够在40kbps到2Mbps之间工作<br>对CIF和QCIF分辨率的视频进行编解码（即亮度分辨率分别是352x288和176x144，色度采用4:2:0采样，分辨率分别是176x144和88x72）, 它们是一种国际化的标准图像格式,不同硬件之间共同约定的统一格式</p>
<h2 id="H-261的实现原理"><a href="#H-261的实现原理" class="headerlink" title="H.261的实现原理"></a>H.261的实现原理</h2><p>使用帧间预测来消除荣誉,使用了大量的矢量运动来进行运动补偿:分析相似图片的规律,将它们不变的地方保留下来,变动的地方按照位移编码规律的出一个计算方式,并根据这个计算规在解码的时候则自动生成中间帧(由于是可以计算出来的,所以中间帧被丢掉)<br>变换编码部分使用了一个8x8的离散余弦变换来消除空域的冗余:<br>然后对变换后的系数进行阶梯量化<br>再对变换系数进行Zig-zag(模式填充矩阵,安某种规则对矩阵进行数据填充)扫描并进行熵编码来消除冗余的统计（编码过程中按熵原理不丢失任何信息的编码。）</p>
<h2 id="视频编码格式-H-264"><a href="#视频编码格式-H-264" class="headerlink" title="视频编码格式-H.264"></a>视频编码格式-H.264</h2><p>H.264目前的应用最广泛的的视频编码格式,是由视频编码专家组和动态图像专家组提出的视频解码器标准,名字有很多,如H.264/AVC（或者AVC/H.264或者H.264/MPEG-4 AVC或MPEG-4/H.264 AVC`</p>
<p>国际上制定视频编解码技术的组织有两个，一个是“国际电联（ITU-T）”，它制定的标准有H.261、H.263、H.263+等，另一个是“国际标准化组织（ISO）”它制定的标准有MPEG-1、MPEG-2、MPEG-4等。而H.264则是由两个组织联合组建的联合视频组（JVT）共同制定的新数字视频编码标准，所以它既是ITU-T的H.264，又是ISO/IEC的MPEG-4高级视频编码（Advanced Video Coding，AVC）的第10 部分。因此，不论是MPEG-4 AVC、MPEG-4 Part 10，还是ISO/IEC 14496-10，都是指H.264。</p>
<h2 id="H-264编解码流程"><a href="#H-264编解码流程" class="headerlink" title="H.264编解码流程"></a>H.264编解码流程</h2><p>帧间和帧内预测(Estimation)<br>变换(Transform)和反变换<br>量化和反量化<br>环路滤波<br>熵编码</p>
<h2 id="H-264的优势"><a href="#H-264的优势" class="headerlink" title="H.264的优势"></a>H.264的优势</h2><p>编码效率高: 同H.263等标准的特率效率相比,节省约一半的时间。<br>高质量的视频画面: 能够在较低的带宽传送高质量的图像<br>网络适应能力强: 可以在低延迟和无延迟的的场景下工作,不同的环境不同的传输和播放熟虑,提供丰富的错误处理工具,很好的控制或消除丢包和误码<br>采用混合编码个够: 使用了DCT+DPCM的编码个够,此外还增加了运动估计,帧内预测,多帧预测,基于内容的变长编码,4<em>4二维整数变换等新的编码方式<br>编码选项少,降低了编码时开发的复杂的度<br>较高的计算复杂度,相比H.263计算更为复杂<br>编码方式<br>帧内预测编码: 利用相邻宏块的空间相关性(相似属性),预测剩余位置的属性进行压缩编码,为了满足不同场景,宏快和取点数以及取点方向各有差异,有4</em>4,8<em>8,16</em>16的宏块划分, 这种压缩类似于JPEG压缩,在图片色彩越统一,压缩效果越好,压缩后的这帧叫做I帧(I-frame).<br>帧间预测编码: 帧间预测编码利用连续帧中的冗余来进行运动估计和补偿, 总而言之,就是各种找规律,统计分析,将相似部分去掉,可推导有规律部分记录差值计算规则,完全不相似部分则全部记录。 帧间压缩后,很多帧会被组成一组图片(GOP,group of pictures)<br>去块滤波器:自适应去除块效应的滤波器,人们无法识别的信号先去除掉<br>整数变换: 基于4×4像素块的类似于DCT的变换,有减少运算量和复杂度，有利于向定点DSP移植的优点<br>量化:可选52种不同的量化步长<br>熵编码: 采用了两种不同的熵编码方法：通用可变长编码（UVLC）和基于文本的自适应二进制算术编码（CABAC）。</p>
<h2 id="H-264-GOP"><a href="#H-264-GOP" class="headerlink" title="H.264-GOP"></a>H.264-GOP</h2><p>上面提到在帧间编码后,会压缩生成一组图片(GOP),GOP中主要保留有三种不同的帧.</p>
<p>1.I-frame,关键帧,独立帧,尺寸最大,也是压缩最快的;</p>
<p>P-frames: 预测帧,基于I-frames或P-frames的可预测的图片进行编码得到的,P-frames可以引用最近预测的P-frames或一组I-frames;<br>B-frames，双向帧,基于使用之前和之后的帧信息进行编码后得到的帧。几乎不需要存储空间，但其解码过程会耗费很长时间，因为它依赖于周围其他的帧.<br>H.264-视图编码<br>Baseline: 支持I/P 帧，只支持无交错和CAVLC，一般用于低阶或需要额外容错的应用，比如视频通话、手机视频等；<br>Main：提供I/P/B 帧，支持无交错和交错，提供对于CAVLC 和CABAC 的支持，用于主流消费类电子产品规格如低解码的mp4、便携的视频播放器、PSP和Ipod等。<br>High：在Main的基础上增加了8x8 内部预测、自定义量化、无损视频编码和更多的YUV 格式（如4：4：4）用于广播及视频碟片存储（蓝光影片），高清电视的应用。</p>
<h2 id="视频信息查看"><a href="#视频信息查看" class="headerlink" title="视频信息查看"></a>视频信息查看</h2><p>Mac上没有什么好用的软件来查看视频信息,可以通过ffmpeg或ffprobe命令在指定<code>-i</code>(information)加上文件名来查看视频的具体信息，如下是终端输出的视频信息</p>
<figure class="highlight shell"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br></pre></td><td class="code"><pre><span class="line">... ffmpegdemo % ffprobe</span><br><span class="line"></span><br><span class="line">Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mov':</span><br><span class="line">  Metadata:</span><br><span class="line">    major_brand     : qt   </span><br><span class="line">    minor_version   : 0</span><br><span class="line">    compatible_brands: qt  </span><br><span class="line">    creation_time   : 2021-02-05T02:51:34.000000Z</span><br><span class="line">    com.apple.quicktime.make: Apple</span><br><span class="line">    com.apple.quicktime.model: MacBookPro15,1</span><br><span class="line">    com.apple.quicktime.software: Mac OS X 10.15.6 (19G2021)</span><br><span class="line">    com.apple.quicktime.creationdate: 2021-02-05T10:50:55+0800</span><br><span class="line">  Duration: 00:00:26.63, start: 0.000000, bitrate: 2028 kb/s  </span><br><span class="line">    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 766x1334 [SAR 1:1 DAR 383:667], 2015 kb/s, 59.93 fps, 60 tbr, 6k tbn, 12k tbc (default)</span><br><span class="line">    Metadata:</span><br><span class="line">      creation_time   : 2021-02-05T02:51:34.000000Z</span><br><span class="line">      handler_name    : Core Media Video</span><br><span class="line">      encoder         : H.264</span><br></pre></td></tr></tbody></table></figure>

<ul>
<li>参数介绍</li>
</ul>
<figure class="highlight text"><table><tbody><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line">Vidoe 采用H.264的编码格式和`yuv420p`的颜色编码格式, </span><br><span class="line">766x1334, 分辨率,</span><br><span class="line">2015 kb/s, 码率</span><br><span class="line">59.93 fps, fps为帧率(frame per second)</span><br><span class="line">60 tbr: tb表示time base,视频容器的一个基本定义,与帧率接近,每秒有60个时间单元</span><br><span class="line">6k tbn: time base 表文件层（st）的时间精度),1s=6k</span><br><span class="line">12k tbc: time base 代表视频层（st-&gt;codec）的时间精度,</span><br><span class="line">DAR - display aspect ratio，显示宽高比,播放出来的画面的宽与高之比</span><br><span class="line">SAR - Sample aspect ratio，采样纵横比,表示横向的像素点数和纵向的像素点数的比值，即为我们通常提到的分辨率宽高比</span><br><span class="line">PAR - pixel aspect ratio，单个像素的宽高比，大多数情况像素宽高比为1:1</span><br></pre></td></tr></tbody></table></figure>

<h2 id="参考文章"><a href="#参考文章" class="headerlink" title="参考文章"></a>参考文章</h2><p><a target="_blank" rel="noopener" href="https://baike.baidu.com/item/H.264/1022230?fr=aladdin">百度百科-H.264</a><br><a target="_blank" rel="noopener" href="http://ddrv.cn/a/232548">ffmpeg 的 tbr tbc 和 tbn的意义</a><br><a target="_blank" rel="noopener" href="https://edu.csdn.net/course/detail/2777">H.264/AVC视频编解码技术详解-收费课程</a></p>

                
            </div>
            <hr/>

            

    <div class="reprint" id="reprint-statement">
        
            <div class="reprint__author">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-user">
                        jiodg45:
                    </i>
                </span>
                <span class="reprint-info">
                    <a href="/jiodg45/about" rel="external nofollow noreferrer">Longxiang.guo</a>
                </span>
            </div>
            <div class="reprint__type">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-link">
                        文章链接:
                    </i>
                </span>
                <span class="reprint-info">
                    <a href="https://jiodg45.gitee.io/jiodg45/jiodg45/2021/03/11/audio-visual/ffmpeg-3/">https://jiodg45.gitee.io/jiodg45/jiodg45/2021/03/11/audio-visual/ffmpeg-3/</a>
                </span>
            </div>
            <div class="reprint__notice">
                <span class="reprint-meta" style="font-weight: bold;">
                    <i class="fas fa-copyright">
                        版权声明:
                    </i>
                </span>
                <span class="reprint-info">
                    本博客所有文章除特別声明外，均采用
                    <a href="https://creativecommons.org/licenses/by/4.0/deed.zh" rel="external nofollow noreferrer" target="_blank">CC BY 4.0</a>
                    许可协议。转载请注明来源
                    <a href="/jiodg45/about" target="_blank">Longxiang.guo</a>
                    !
                </span>
            </div>
        
    </div>

    <script async defer>
      document.addEventListener("copy", function (e) {
        let toastHTML = '<span>复制成功，请遵循本文的转载规则</span><button class="btn-flat toast-action" onclick="navToReprintStatement()" style="font-size: smaller">查看</a>';
        M.toast({html: toastHTML})
      });

      function navToReprintStatement() {
        $("html, body").animate({scrollTop: $("#reprint-statement").offset().top - 80}, 800);
      }
    </script>



            <div class="tag_share" style="display: block;">
                <div class="post-meta__tag-list" style="display: inline-block;">
                    
                        <div class="article-tag">
                            
                                <a href="/jiodg45/tags/audio/">
                                    <span class="chip bg-color">audio</span>
                                </a>
                            
                                <a href="/jiodg45/tags/ffmpeg/">
                                    <span class="chip bg-color">ffmpeg</span>
                                </a>
                            
                        </div>
                    
                </div>
                <div class="post_share" style="zoom: 80%; width: fit-content; display: inline-block; float: right; margin: -0.15rem 0;">
                    <link rel="stylesheet" type="text/css" href="/jiodg45/libs/share/css/share.min.css">
<div id="article-share">

    
    <div class="social-share" data-sites="twitter,facebook,google,qq,qzone,wechat,weibo,douban,linkedin" data-wechat-qrcode-helper="<p>微信扫一扫即可分享！</p>"></div>
    <script src="/jiodg45/libs/share/js/social-share.min.js"></script>
    

    

</div>

                </div>
            </div>
            
        </div>
    </div>

    

    

    

    

    

    

    

    

    

<article id="prenext-posts" class="prev-next articles">
    <div class="row article-row">
        
        <div class="article col s12 m6" data-aos="fade-up">
            <div class="article-badge left-badge text-color">
                <i class="fas fa-chevron-left"></i>&nbsp;上一篇</div>
            <div class="card">
                <a href="/jiodg45/2021/03/11/flutter/flutter-animate/">
                    <div class="card-image">
                        
                        
                        <img src="/jiodg45/medias/featureimages/15.jpg" class="responsive-img" alt="Flutter动画">
                        
                        <span class="card-title">Flutter动画</span>
                    </div>
                </a>
                <div class="card-content article-content">
                    <div class="summary block-with-text">
                        
                            Flutter Bloc实战总结
                        
                    </div>
                    <div class="publish-info">
                        <span class="publish-date">
                            <i class="far fa-clock fa-fw icon-date"></i>2021-03-11
                        </span>
                        <span class="publish-author">
                            
                            <i class="fas fa-bookmark fa-fw icon-category"></i>
                            
                            <a href="/jiodg45/categories/flutter/" class="post-category">
                                    flutter
                                </a>
                            
                            
                        </span>
                    </div>
                </div>
                
                <div class="card-action article-tags">
                    
                    <a href="/jiodg45/tags/flutter/">
                        <span class="chip bg-color">flutter</span>
                    </a>
                    
                </div>
                
            </div>
        </div>
        
        
        <div class="article col s12 m6" data-aos="fade-up">
            <div class="article-badge right-badge text-color">
                下一篇&nbsp;<i class="fas fa-chevron-right"></i>
            </div>
            <div class="card">
                <a href="/jiodg45/2021/03/11/audio-visual/ffmpeg-5/">
                    <div class="card-image">
                        
                        
                        <img src="/jiodg45/medias/featureimages/4.jpg" class="responsive-img" alt="FFmpeg笔记(五)">
                        
                        <span class="card-title">FFmpeg笔记(五)</span>
                    </div>
                </a>
                <div class="card-content article-content">
                    <div class="summary block-with-text">
                        
                            FFmpeg笔记
                        
                    </div>
                    <div class="publish-info">
                            <span class="publish-date">
                                <i class="far fa-clock fa-fw icon-date"></i>2021-03-11
                            </span>
                        <span class="publish-author">
                            
                            <i class="fas fa-bookmark fa-fw icon-category"></i>
                            
                            <a href="/jiodg45/categories/ffmpeg/" class="post-category">
                                    ffmpeg
                                </a>
                            
                            
                        </span>
                    </div>
                </div>
                
                <div class="card-action article-tags">
                    
                    <a href="/jiodg45/tags/audio/">
                        <span class="chip bg-color">audio</span>
                    </a>
                    
                    <a href="/jiodg45/tags/ffmpeg/">
                        <span class="chip bg-color">ffmpeg</span>
                    </a>
                    
                </div>
                
            </div>
        </div>
        
    </div>
</article>

</div>



<!-- 代码块功能依赖 -->
<script type="text/javascript" src="/jiodg45/libs/codeBlock/codeBlockFuction.js"></script>

<!-- 代码语言 -->

<script type="text/javascript" src="/jiodg45/libs/codeBlock/codeLang.js"></script>


<!-- 代码块复制 -->

<script type="text/javascript" src="/jiodg45/libs/codeBlock/codeCopy.js"></script>


<!-- 代码块收缩 -->

<script type="text/javascript" src="/jiodg45/libs/codeBlock/codeShrink.js"></script>


    </div>
    <div id="toc-aside" class="expanded col l3 hide-on-med-and-down">
        <div class="toc-widget card" style="background-color: white;">
            <div class="toc-title"><i class="far fa-list-alt"></i>&nbsp;&nbsp;目录</div>
            <div id="toc-content"></div>
        </div>
    </div>
</div>

<!-- TOC 悬浮按钮. -->

<div id="floating-toc-btn" class="hide-on-med-and-down">
    <a class="btn-floating btn-large bg-color">
        <i class="fas fa-list-ul"></i>
    </a>
</div>


<script src="/jiodg45/libs/tocbot/tocbot.min.js"></script>
<script>
    $(function () {
        tocbot.init({
            tocSelector: '#toc-content',
            contentSelector: '#articleContent',
            headingsOffset: -($(window).height() * 0.4 - 45),
            collapseDepth: Number('0'),
            headingSelector: 'h2, h3, h4'
        });

        // modify the toc link href to support Chinese.
        let i = 0;
        let tocHeading = 'toc-heading-';
        $('#toc-content a').each(function () {
            $(this).attr('href', '#' + tocHeading + (++i));
        });

        // modify the heading title id to support Chinese.
        i = 0;
        $('#articleContent').children('h2, h3, h4').each(function () {
            $(this).attr('id', tocHeading + (++i));
        });

        // Set scroll toc fixed.
        let tocHeight = parseInt($(window).height() * 0.4 - 64);
        let $tocWidget = $('.toc-widget');
        $(window).scroll(function () {
            let scroll = $(window).scrollTop();
            /* add post toc fixed. */
            if (scroll > tocHeight) {
                $tocWidget.addClass('toc-fixed');
            } else {
                $tocWidget.removeClass('toc-fixed');
            }
        });

        
        /* 修复文章卡片 div 的宽度. */
        let fixPostCardWidth = function (srcId, targetId) {
            let srcDiv = $('#' + srcId);
            if (srcDiv.length === 0) {
                return;
            }

            let w = srcDiv.width();
            if (w >= 450) {
                w = w + 21;
            } else if (w >= 350 && w < 450) {
                w = w + 18;
            } else if (w >= 300 && w < 350) {
                w = w + 16;
            } else {
                w = w + 14;
            }
            $('#' + targetId).width(w);
        };

        // 切换TOC目录展开收缩的相关操作.
        const expandedClass = 'expanded';
        let $tocAside = $('#toc-aside');
        let $mainContent = $('#main-content');
        $('#floating-toc-btn .btn-floating').click(function () {
            if ($tocAside.hasClass(expandedClass)) {
                $tocAside.removeClass(expandedClass).hide();
                $mainContent.removeClass('l9');
            } else {
                $tocAside.addClass(expandedClass).show();
                $mainContent.addClass('l9');
            }
            fixPostCardWidth('artDetail', 'prenext-posts');
        });
        
    });
</script>

    

</main>




    <footer class="page-footer bg-color">
    
        <link rel="stylesheet" href="/jiodg45/libs/aplayer/APlayer.min.css">
<style>
    .aplayer .aplayer-lrc p {
        
        display: none;
        
        font-size: 12px;
        font-weight: 700;
        line-height: 16px !important;
    }

    .aplayer .aplayer-lrc p.aplayer-lrc-current {
        
        display: none;
        
        font-size: 15px;
        color: #42b983;
    }

    
    .aplayer.aplayer-fixed.aplayer-narrow .aplayer-body {
        left: -66px !important;
    }

    .aplayer.aplayer-fixed.aplayer-narrow .aplayer-body:hover {
        left: 0px !important;
    }

    
</style>
<div class="">
    
    <div class="row">
        <meting-js class="col l8 offset-l2 m10 offset-m1 s12"
                   server="netease"
                   type="playlist"
                   id="503838841"
                   fixed='true'
                   autoplay='false'
                   theme='#42b983'
                   loop='all'
                   order='random'
                   preload='auto'
                   volume='0.7'
                   list-folded='true'
        >
        </meting-js>
    </div>
</div>

<script src="/jiodg45/libs/aplayer/APlayer.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/meting@2/dist/Meting.min.js"></script>

    
    <div class="container row center-align" style="margin-bottom: 0px !important;">
        <div class="col s12 m8 l8 copy-right">
            Copyright&nbsp;&copy;
            
                <span id="year">2019-2021</span>
            
            <span id="year">2019</span>
            <a href="/jiodg45/about" target="_blank">Longxiang.Guo</a>
            |&nbsp;Powered by&nbsp;<a href="https://hexo.io/" target="_blank">Hexo</a>
            |&nbsp;Theme&nbsp;<a href="https://github.com/blinkfox/hexo-theme-matery" target="_blank">Matery</a>
            <br>
            
            
            
            
            
            
            <span id="busuanzi_container_site_pv">
                |&nbsp;<i class="far fa-eye"></i>&nbsp;总访问量:&nbsp;<span id="busuanzi_value_site_pv"
                    class="white-color"></span>&nbsp;次
            </span>
            
            
            <span id="busuanzi_container_site_uv">
                |&nbsp;<i class="fas fa-users"></i>&nbsp;总访问人数:&nbsp;<span id="busuanzi_value_site_uv"
                    class="white-color"></span>&nbsp;人
            </span>
            
            <br>
            
            <br>
            
        </div>
        <div class="col s12 m4 l4 social-link social-statis">
    <a href="https://github.com/LongXiangGuo" class="tooltipped" target="_blank" data-tooltip="访问我的GitHub" data-position="top" data-delay="50">
        <i class="fab fa-github"></i>
    </a>



    <a href="mailto:290657563@qq.com" class="tooltipped" target="_blank" data-tooltip="邮件联系我" data-position="top" data-delay="50">
        <i class="fas fa-envelope-open"></i>
    </a>







    <a href="tencent://AddContact/?fromId=50&fromSubId=1&subcmd=all&uin=290657563" class="tooltipped" target="_blank" data-tooltip="QQ联系我: 290657563" data-position="top" data-delay="50">
        <i class="fab fa-qq"></i>
    </a>







</div>
    </div>
</footer>

<div class="progress-bar"></div>


    <!-- 搜索遮罩框 -->
<div id="searchModal" class="modal">
    <div class="modal-content">
        <div class="search-header">
            <span class="title"><i class="fas fa-search"></i>&nbsp;&nbsp;搜索</span>
            <input type="search" id="searchInput" name="s" placeholder="请输入搜索的关键字"
                   class="search-input">
        </div>
        <div id="searchResult"></div>
    </div>
</div>

<script type="text/javascript">
$(function () {
    var searchFunc = function (path, search_id, content_id) {
        'use strict';
        $.ajax({
            url: path,
            dataType: "xml",
            success: function (xmlResponse) {
                // get the contents from search data
                var datas = $("entry", xmlResponse).map(function () {
                    return {
                        title: $("title", this).text(),
                        content: $("content", this).text(),
                        url: $("url", this).text()
                    };
                }).get();
                var $input = document.getElementById(search_id);
                var $resultContent = document.getElementById(content_id);
                $input.addEventListener('input', function () {
                    var str = '<ul class=\"search-result-list\">';
                    var keywords = this.value.trim().toLowerCase().split(/[\s\-]+/);
                    $resultContent.innerHTML = "";
                    if (this.value.trim().length <= 0) {
                        return;
                    }
                    // perform local searching
                    datas.forEach(function (data) {
                        var isMatch = true;
                        var data_title = data.title.trim().toLowerCase();
                        var data_content = data.content.trim().replace(/<[^>]+>/g, "").toLowerCase();
                        var data_url = data.url;
                        data_url = data_url.indexOf('/') === 0 ? data.url : '/' + data_url;
                        var index_title = -1;
                        var index_content = -1;
                        var first_occur = -1;
                        // only match artiles with not empty titles and contents
                        if (data_title !== '' && data_content !== '') {
                            keywords.forEach(function (keyword, i) {
                                index_title = data_title.indexOf(keyword);
                                index_content = data_content.indexOf(keyword);
                                if (index_title < 0 && index_content < 0) {
                                    isMatch = false;
                                } else {
                                    if (index_content < 0) {
                                        index_content = 0;
                                    }
                                    if (i === 0) {
                                        first_occur = index_content;
                                    }
                                }
                            });
                        }
                        // show search results
                        if (isMatch) {
                            str += "<li><a href='" + data_url + "' class='search-result-title'>" + data_title + "</a>";
                            var content = data.content.trim().replace(/<[^>]+>/g, "");
                            if (first_occur >= 0) {
                                // cut out 100 characters
                                var start = first_occur - 20;
                                var end = first_occur + 80;
                                if (start < 0) {
                                    start = 0;
                                }
                                if (start === 0) {
                                    end = 100;
                                }
                                if (end > content.length) {
                                    end = content.length;
                                }
                                var match_content = content.substr(start, end);
                                // highlight all keywords
                                keywords.forEach(function (keyword) {
                                    var regS = new RegExp(keyword, "gi");
                                    match_content = match_content.replace(regS, "<em class=\"search-keyword\">" + keyword + "</em>");
                                });

                                str += "<p class=\"search-result\">" + match_content + "...</p>"
                            }
                            str += "</li>";
                        }
                    });
                    str += "</ul>";
                    $resultContent.innerHTML = str;
                });
            }
        });
    };

    searchFunc('/jiodg45/search.xml', 'searchInput', 'searchResult');
});
</script>

    <!-- 回到顶部按钮 -->
<div id="backTop" class="top-scroll">
    <a class="btn-floating btn-large waves-effect waves-light" href="#!">
        <i class="fas fa-arrow-up"></i>
    </a>
</div>


    <script src="/jiodg45/libs/materialize/materialize.min.js"></script>
    <script src="/jiodg45/libs/masonry/masonry.pkgd.min.js"></script>
    <script src="/jiodg45/libs/aos/aos.js"></script>
    <script src="/jiodg45/libs/scrollprogress/scrollProgress.min.js"></script>
    <script src="/jiodg45/libs/lightGallery/js/lightgallery-all.min.js"></script>
    <script src="/jiodg45/js/matery.js"></script>

    <!-- Baidu Analytics -->

    <!-- Baidu Push -->

<script>
    (function () {
        var bp = document.createElement('script');
        var curProtocol = window.location.protocol.split(':')[0];
        if (curProtocol === 'https') {
            bp.src = 'https://zz.bdstatic.com/linksubmit/push.js';
        } else {
            bp.src = 'http://push.zhanzhang.baidu.com/push.js';
        }
        var s = document.getElementsByTagName("script")[0];
        s.parentNode.insertBefore(bp, s);
    })();
</script>

    
    <script src="/jiodg45/libs/others/clicklove.js" async="async"></script>
    
    
    <script async src="/jiodg45/libs/others/busuanzi.pure.mini.js"></script>
    

    

    

    <!--腾讯兔小巢-->
    
    

    

    

    
    <script src="/jiodg45/libs/instantpage/instantpage.js" type="module"></script>
    

</body>

</html>
